On Thu, 15 Nov 2012, Greg KH wrote: > On Wed, Nov 07, 2012 at 06:36:46PM +0530, Bhavik Kothari wrote: > > Hi Greg, > > > > Our host controller sets PRC and CSC bits at the time of initialization > > even though no USB device is attached. At the time of initialization, > > hub_probe() gets called and in-turn it calls hub_activate(). > > hub_activate() clears the CSC bit, but PRC bit does not get cleared (in > > linux 3.6.1). hub_events() has functionality to clear the PRC bit, but > > initially there is no events from HUB, so hub_events() may not clear the > > PRC bit. Due to this behavior, when we try to insert a USB device, > > interrupt does not generate (because, earlier, PRC bit was set and not > > cleared) and USB device does not get enumerated. > > > > Below Patch allows to clear PRC bit in hub_activate() function. So, > > above issue gets resolved. > > > > This patch is currently against a linux 3.6.1 kernel, for the x86 > > architecture. > > The USB code works on all architectures :) > > > Let me know in case of any concern. > > So why do this on all host controllers? Why not just clear the bit for > your devices based on a device id or some other identifier? What > happens if you clear this on a different manufacturer's device? This bit should never be set at this time, regardless of the manufacturer. It's okay to clear it always. A question remains as to whether more should be done in xhci-hcd for controllers that start out in similar weird states. > Also, I would like to get an ack from Alan on this before I accept it. The patch is okay with me. But we should get Sarah's opinion too. Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
